Impact of Considering Surger Arresters to Reduce Lightning Induced Voltage: emphasis on the Grounding Modeling

Lightning-related phenomena are one of the most dangerous factors affecting the overhead distribution systems. Said that, protective measures to reduce lightning damages are an important issue to guarantee distribution line reliability. The most widely employed protective measures against lightning are: shield wires, surge arresters, and increasing the line insulation level, usually by increasing the length of insulator strings. Among the aforementioned techniques, one that deserves a special attention is installing lightning arresters, since it can be very effective and commonly used in reducing lightning overvoltage. In this way, this paper presents a comparative study of the induced overvoltage calculation along insulator strings due to indirect lightning strikes in the distribution lines with and without the installation of surger arresters and comparing results considering a simple and rigorous modeling of the pole-footing grounding system. Furthermore, a simplified representation of the model of the pole-footing grounding system, in which the surge arresters will be installed, commonly adopted may lead to an underestimation of the overvoltage. The results point that the surge arresters are able to isolate the propagation of the induced voltages in adjacent poles by positioning them at poles in alternate pattern. The maximum voltage difference found when considering the rigorous model instead of the simplified model of the pole-footing grounding system, for the cases studied, was around 6.42%.